Method for improving water-resistant characteristics of resins and resinous articles, and resinous products resulting therefrom



Patented Dec. 21, 1948 LIETHOD FOR DIPROVING WATER-RESIST- ANTCHARACTERISTICS OF RESINS AND RESINOUS ARTICLES,

AND RESINOUS PRODUCTS RESULTING THEREFROM Loring Coes, 'Jr., Brookiield,Mass assignor to Norton Company, Worcester, Mass a corporation ofMassachusetts No Drawing. Original application September 28,

1942, Serial No. 459.956. Divided and this application April 1, 1947,Serial No. 738,720

application, Serial No. 459,956, filed September 28, 1942, nowabandoned.

One of the objects of this invention is to provide an abrasive articleof the above-mentioned character that will have good resistance to waterwhere such abrasive articles have to be operated in the presence of orcontact with a liquid coolant such as water; another object is toprovide a simple and practical method for making such an abrasivearticle to give it good water-repellant or water resisting propertieswithout detrimem.

tally detracting from the advantages achievable in structure, operationand method of making abrasive articles utilizing resinous bonds of theabove-mentioned character. Another object is to provide an abrasivearticle in which a halide, such as hydrogen chloride, can be madeavailable at the grinding line and which has superior water-resistantproperties achieved in a manner which will not detrimentally affect theliberation of, for example. hydrogen chloride at the grinding line.

Another object is to provide a resin that will resist weakening underthe effects of water. Another object is to provide a heat-curable resinthat can be cured without swelling during curing and that will also havesuperior water-resistant properties in the hardened or cured product.

Another object is to provide a practical and eihcient method of makingstrong and wateror without abrasive grains admixed therewith and thatcan be readily carried on in practice. Other objects will be in partobvious or-in part pointed out hereinafter.

The invention accordingly consists in the features of construction,combinations of elements. arrangements of parts, and in the severalsteps and relation and order of each of said steps to one or more of theothers thereof, all as will be illustratively described herein, and thescope of the application of which will be indicated in the fol lowingclaims. g

It has heretofore been proposed to make grinding wheels and other solidabrasivecompcsitions 9 Claims. (Cl. 260-39) 4Q. resistant resins, withor without fillers, and with Q;

or attraction of this bonded or linked halide for bonded with primaryaromatic amine-formaldehyde resins that are hardened with poly-halogencompounds, several illustrative examples of which are hereinafter setforth, and it has been found that satisfactory and good abrasivearticles, with good grinding characteristics, can thus be made.Moreover, according to such prior proposals, resins so hardened havebeen found to have many characteristics making them desirable for use infields other than the field of abrasive articles. Resins and resinousbonds so made have, in the field of abrasive articles, the uniquecharacteristic of making available or releasing at the grinding line anacid halide such as hydrogen chloride, hydrogen bromide or the like, tocoact in achieving improved or superior grinding action. I have found,however, that grinding wheels so made develop various degrees ofdeficiency in repelling or resisting water where the wheel, as in someindustrial uses, has to be operated during the grinding action under thecooling action of water, the same wheels, however, standing upexcellently and with good results when operated dry such as forsnagging, with the result that the wheel loses strength and itsdurability and grinding action become impaired.

I have discovered a reliable and eficient method and means for obviatingpr preventing the development of such deficiencies and I am thus enabledto produce both a iesin and a resinbonded abrasive article which standup equally well when used or operated dry or devoid of water or moistureand when used or operated wet or in the presence of moisture or water.

In the production of resins or resinous products or resin-bondedabrasive articles, hardened by such poly-halogen compounds, apolymerization takes place in which the cross-linkage includes a linkageor bond of the halide, such as hydrogen chloride, to an amino group orto one or more nitrogen atoms and I believe that it is the afiinitywater which is the cause of deficiency in water resistance, a deficiencywhich is sometimes of progressively increasing magnitude; as a resultthe resin or resinous band can become absorptive of waterand because ofthe linkage of the halide as part of the polymer, the halide isuniformly distributedgas it were, throughout the mass of the resin or ofthe resinous bond, and it is accordingly readily and uniformlythroughout the mass available for progressive absorption or attractionof water and for possible interaction therewith. Physically the eilectis somewhatlike a swelling of what is otherwise a hard, tough andsteeper strong resinous body, and is accompanied by structural weakeningand loss of strength where the resin orjresin-bonded abrasive issubjected to moisture or-water.

According to my invention, '1 am enabled, by the above-mentionedcross-linking, to retain a uniform distribution of the halide,illustratively hydrogen chloride, but to convert itinto a phase and intoa physical state such that, while still available for release at thegrinding line when the resin is used as a bond for abrasive grain, it isnot available or is in effect isolated so that it cannot function toattract or absorb-the water 4 such as emery, corundum, dense "regular"fused alumina, porous white fused alumina; silicon carbide and otherhard carbides; quartz; glass; garnet; or diamonds. Two or more of theseabrasives may be mixed, if desired.

the oven to make organic bonded grinding wheels because this combinationof steps and features is the cheapest to carry out and, furthermore, I

enerally gives uniform results. In the 'dry 1 granular mix method theabrasive grains are 1 placed in a mixing pan and are then wet withthroughout the resinous mass. Henceswelling,

the loss of strength, and other detrimentalactions otherwise caused bymoisture or water are precluded from taking place. In effect, :thehalide becomes, according to my invention as I understand it, uniformlydistributed in gen infinite number of very minute, small physicalentitles of which each is totally enclosed in a cell of the resin fromthe polymer of which the halide is in effect physically and chemicallyIdetached, though the cross-linking accompanying the polymerization hasbeen eil'ective to achieve uniform distribution initially of the halidethroughout i'the mass of the resin or resinousbond. Accordingly, thehardened resin is g ven good water-resistant properties and the abrasivearticle can operate and-stand up just about as well when running wet aswhen To better understand these features or my invention, severalillustrations of primary'aromatic amine-formaldehyde resins hardenedwith poly-halogen. compounds are hereinafter set forth in connectionwith correspondingly iilus trative structures of abrasive articles such.as grinding wheels, to show first how the halide becomes linked as partof the polymer. and; .t'hen I shall describe the means and method that Iemploy toconvert the halide to a different phase or physical state topreclude it from attracting, absorbing or reacting with water to swelland weaken the structure, and though the illustrations are set forth inconnection with the making of abrasive or grinding wheels, suchillustrations are not to be interpreted in a limiting sense fer to useis aniline. Aniline or one of the other primary aromatic aminesmentioned, or mixtures of two or moreof such amines, is reacted withformaldehyde HCHO in the presence of a strong acid to produce, a longchain polymer which, when an excess of formaldehyde above thestoichiometric proportions is used, for example 20% excess, has adjacentchains connected with methylene CH2-- groups to form a tough.heat-resistant, semi-thermoplastic resin. I may add some of theformaldehyde after the initial condensation, in the form ofparaformaldehyde, or by the addition of hexa-methylene-tetramine.

Since the invention is best illustrated inrelation to grinding wheelsand other solid abrasive compositions and articles, I provide a quantityof abrasive grain. Any abrasive grain may be used, for example, any ofthe varieties of alumina,

a suitable liquid; then powdered fusible resin This method incontradistinction to the use of the hot press with or without theautoclave and vice verse, has the advantage that ordinary ovens, inwhich thousands of green" wheels can be stacked, are used; the hydraulicpress is tied up by a given wheel for thirty seconds instead of thirtyminutes, and the press need have no heated platens. This wetting of theabrasive grains by a liquid is called plasticizingf' It is preferredthat the wettant be a solvent for the resin.

In the commercial manufacture of alinineformaldehyde resin bondedgrinding wheels and other solid abrasive products, only furfural hasbeen used as this plasticizer-wettant. (Other aromatic-amine-aldehydepolymers have not been used commercially for the manufacture of grindingwheels and other solid abrasive products so far as I am aware.) thepolymer and, therefore, converts it to the "infus'ible condition. A'stoichiometric quantity of aniline and formaldehyde condensed in thepresence of a strong acid is believed to produce a resin which isstructurally represented thus:

Such a resin cross-linked with furfural is believed to be representedthus: 32%.. i m. UM 1 t it... UL

Ethers may be employed .as plasticizers and hardening agents, such asare dealt with in my co-pending application, Serial No. 445,801, filedJune 4, 1942, now Patent No. 2,309,575, producing a polymer having ahalide, preferably and usually hydrogen chloride, attached or linkedthereto.

Thus, I may employ dichlor diethyl .ether or other polyglycol dichlorideas the hardening agent and, in making abrasive articles, as the wettant-The furfural cross-links I believe it cross-links theaniline-formaldehyde polymer thus:

It will be noted that chlorine now appears in the amino group. When agrinding wheel thus made is used to grind, the heat generated bygrinding releases hydrogen chloride at the grinding line.

Tri-glycol dichloride is written thus:

It-will thus be seen that it is definitely related to dichlor diethylether which can also be called diglycol dichloride. Other polyglycoldichlorides may also be used. For instance, tetra-glycol dichloridewould be written thus:

However, the compounds of large molecular weight, that is, havingadditional C2H4 groups, are solids and are not usable. Therefore, I useany poly-glycol dichloride selected from the group consisting of thedi-, tri-, tetra-, and penta-poly-glycol dichlorides or mixtures of twoor more ofv them. These ethers are monomeric compounds.

Ezcample I Two hundred and ten grams of #80 grit fused alumina isstirred .with four and five-tenths cubic centimeters of dichlor diethylether. Twelve and eight-tenths grams of soluble anhydrite (09.804) andforty-two and eight-tenths grams of aniline formaldehyde resin made fromone and five-hundredths molecular proportions of formaldehyde are added.The whole is mixed. The free flowing granular mix is cold molded under apressure of three tons to the square inch. The cold molded objects arethen packed in sand and baked for eight hours at 100 C. Test bars madein this way showed a modulus of rupture of 2600 pounds to the squareinch which indicates a high tensile strength for abrasive productsmadewith this kind of resin.

Example II Eight hundred and fifty-eight cubic centimeters of aniline isdissolved in eight liters of water containing nine and three-tenths molsof hydrochloric acid. To this is added seven hundred and fifty cubiccentimeters of formalin solution containing four-tenths gram offormaldehyde per cubic centimeter. After standing for one hour, aquantity 01' sodium hydrexide is added equivalent to the hydrochloricacid present. The precipitated resin is filtered, washed, dried, andground to a fine powder. Into each ten pounds of this powdered resin Imix two and two-tenths pounds 01' polyvinyl chloride. Twenty-eight andone-tenth pounds of a porous relatively pure grade of fused aluminaabrasive grit size is wet with twenty-three hundredths of a pound oitriglycol dichloride. Then five and nine-tenths pounds of the aboveresin is intimately mixed with the fused alumina wet with dichlordiethyl I ether spread in an eighteen inch mold with a five inch arbor,cold pressed under a pressure of three tons to the square inch,transferred to an oven, and baked for one hour and a half at 160 C.

Erample III Thirty-seven pounds of #14 mesh grit size fused aluminaabrasive is placed in a mixing,

Example IV Eight hundred and eighty-five grams of #60 mesh grit sizefused alumina is wet with twentyfive cubic centimeters of triglycoldichloride. One hundred and sixty grams of the powdered resin fromExample II and forty-nine grams of chlorinated eicosane is added. Aftermixing to form a dry granular mix, it is spread in an eight inch moldand pressed under a pressure of one hundred and fifty tons per squareinch and then stripped from the mold and baked at a temperature of C.for eight hours.

Fully chlorinated eicosane is not readily available and as a practicalmatter, partially chlorinated eicosane is quite satisfactory.Furthermore, the name eicosane has been chosenas the proper chemicalname for the product with twenty carbon atoms, more or less, sold underthe trade-mark Chlorcosane, which is probably a mixture of chlorinatedhigh molecular weight parafllnes averaging twenty carbon atoms orthereabouts. Y

For the acid used in condensing the resin, besides hydrochloric andphosphoric acids, any of the following acids or many others may also beused:

' Hydriodicacid Tri-.chlor acetic acid Di-chlor acetic-acid Maleic acidoxalic acid Picric acid Sulphuric acid auaoar The various halogenatedorganic compounds. mentioned herein cross-link the resin at the aminogroups. The dichlor diethyl ether, as previously set forth, cross-linksthe resin at the amino groups. When this ether and also anotherhalogenated compound are used the cross-linking Of-'chalnsis*efleeted byradicals from both the chlorinated ether and the other halogenatedcompound, more or less at random and in proportion to the number ofmolecules of each present. It is believed, therefore, to be unnecessaryto set forth herein any more structuresbut reference is made toco-pending application Serial No. 411,249, flied September 17, 1941, nowabandoned, by my colleague, Samuel 8. Kistler, as-

signed to the assignee hereof, wherein a great many representativestructures which are believed to typify the conditions are set forth. In

said prior application of Kistler, however, no

dichlor diethyl ether is disclosed.

The reason why triglycol dichloride and dichlor diethyl ether arepreferred to furfural is that during the final cure and alkylation. nowater is liberated. If we have resin consisting of chains as follows:

O mO-q F and-we then heat it in the presence of furfural.

the group is used. the alkylation takes place at the amino groups by theshift or linking of the chlorine atoms to the nitrogen atoms, leavingavaflable a bond at each end to connect the nitrogen atoms of adjacentchains (the nitrogen becoming socalled quinquevalent, as in the case ofammonium chloride).

This formation of water during the final curing is detrimental andcauses swelling unless the wheel is being cured under pressure (as in ahot press or in an autoclave) excepting where a long enough time isallowed or the wheel is very porous. Consequently the present inventionpermits cold pressing for the formation of abrasive com- I positionsthat heretofore could not be satisfactorily made by the cold-pressingmethod. However, since dichlor diethyl ether is a good wettant, asolvent for the aniline formaldehyde resin. and a cross-linking agentand, in fact, is an excellent fplasticizer for abrasive grains forcarry;- ing out the dry granular mix method, there is considerableadvantage in using dichlor diethyl ether even though for some reason orother the wheels are to be molded in a hot press. Fur-. thermore,dichlor diethyl ether provides hydrogen chloride which is released atthe grinding line and, therefore, the addition of other halogenatedproducts may be dispensed with where a suflicient quantity of hydrogenchloride for the purpose is provided by the dichlor diethyl ether. Thedichlor diethyl ether has the further advantages over furfural that ithas a lower viscosity. 1

- 8 c a lower surface tension, and is not sublect to deter'ioratiomundernormal storage conditions.

However, mixtures of furfural and dichlor diethyl ether may be used, asthey are miscible in s allproportions. By the use of both furfural andtrlalycol dichloride. I can cause cross-linking at the ortho positionsand also at the amino groups. in accordance with the explanations anddiano in the following example.

' Example V Two hundred and ten grams of so grit fused alumina isstirred with four and live-tenths culiic centimeters of a mixture ofequal parts by weight of furfural and dichlor diethyl ether. Twelve andeight-tenths grams of soluble anhydrite .(CaS OO and forty-two andeight-tenths-grams of aniline formaldehyde resin made from one andiive-hundredths molecular proportions of formaldehyde are added. Thewhole is mixed. The granular mix is molded in shot press for two hoursat ninety pounds steam pressure (160 0.) under a pressure of three tonsto the square inch. In any of the examples, any other monomericpoiyglycol dichloride selected from the group consisting of the di-.tri-, tetraand pentamlyslycoi dichlorides could have been used withsubstantially the same results and also in the 80 same proportions; ofall the compounds mentioned, I prefer triglycoi dichloride because it isa better solvent than diglycol dichloride and more readily availablethan tetraand penta-glycoi dichloride,

with primary aromatic amine formaldehyde resins to form hardened resinsand/or resinous products. and in the polymer they present, asillustrated by the linkagesabove. set forth, the

samefgeneraicharacteristic of a halide usually andpreferablyhydrogen--chloride attached or linked thereto, and there has been in theabove indicated-various of the many advantages that accrue,notonly-in4heresultant structures'but also in the methods of handling ortreating to arrive at such structures.

All ofthese polymers may be said to have a common or the same physicaland chemical characteristic. in. that, because of the above-mentionedcharacteristic linkage of'the halide, the latter is uniformlydistributed throughout the mass-of the resin or of the resinous bond,and in,

that sense the halide is uniformly available throughout the mass forprogressive absorption or attraction of water and for possibleinteraction therewith. Where the resin or resinous'structure, as a finalproduct, has porosity, as is frequently desirable in grinding wheelconstruction, in. which furthermore differing degrees of porosity arede- 1 sirable according to the-differing abrasive characteristicsdesired, such porosity can be of undesired aid in physically bringingwater or moisture, by way of the-pores or cells, to more readyinteraction with or attraction or absorption, by'the' halide, and thepolymers resultin! from the use of the ethers can be, in preparation andtreatment, controlled-togive anyporosiw desired, as for examplein=making- .up grinding wheels, and hence my present invention canbereference first to such polymers. 1 1

Grinding. wheels so constructed with such ing according to circumstancesthe extent of grams already given. Thus rmay proceed as The-above--is-lllustrative of ethers reactible better illustratedxand 'setwforthinitially with polymers, controlled in processing, asby varycompressionof the mix, may therefore be said to be much more susceptible, whenoperated wet as with a water-coolant, to the effects of water ormoisture than the same polymers when initially processed to have zeroporosity. Such effects, as above pointed out, result in structuralweakening, loss of strength of the resin, or resinbonded structure, andin swelling, the effects increasing in intensity or rapidity ofspreading from low values at zero porosity to increasing values as thedegree of porosity increases.

Now, according to my invention, I am enabled to overcome thesedetrimental effects by converting the uniformly distributed halide intoa different phase and virtually into a physical state such that, thoughinitially supplied by the hardening agent and though initially uniformlydistributed throughout the mass due to an initial linkage to or with thepolymer, it now appears in' an infinite number of uniformly distributedvery minute physical entities probably chemically detached or un-bondedfrom the polymer, with each entity substantially totally enclosed in acell of the hardened resin and thus physically isolated againstattraction of orabsorption of or interaction with water or moisture; andyet, under the action of grinding, with the heat evolved, these minutephysical entities of the halide are made available at the grinding line,probably due to and as the cells enclosing the minute entities are wornor otherwise ruptured or broken open. In regard to the above-mentionedchanges of phase or state to achieve such actions as have just beennoted, I incorporate in the mix. in preparing the ingredients forcuring, substances which have the effect and action to remove the halidefrom those atoms in the resin molecule to which they are connected orlinked. such as the atoms indicated in the various illustrative polymerlinkage above set forth and to which the halide. hydrogen chloride, inthese illustrations are connected. The cross-linking, as typified in theiust mentioned cross-linkages representing ind vidual resin molecules.will be seen to have the effect of uniformly distributing the halidethroughout the mass of the resin just as are the molecules of the latterdistributed. but according to my invention the added substances,illustrations of which are about to be set forth, have the effect ofdisconnecting or removing the thusdistributed halide from the quaternarynitrogen atom r atoms in each res n molecule.

Usable substances for these purposes should not be too alkaline for thedesired effects might not be achieved because the too high alkalinitywould slow up or prevent the curing of the resin. Also, it is preferablethat they do not react with the hardening agent, such as the ethersfaster than the hardening agent reacts with the resin. Moreover, byutilizing substances which react slower or with a delayed action ascompared to the rate at which the hardening agent reacts with the resin,I am enabled to achieve certain unique coactions to better and moreefflciently bring about the above-mentioned effects, as is laterexplained in greater detail. They should have sufficient solubility toreact or a solubility to react at the desired rate, and the reactionpreferably should not be such as to cause the formation of gases orvapors which might cause subsequent swelling of the resin or resinousbody during curing.

The substances which. according to this divisional application, can beused are the salts of weak acids. sodium silicate and zinc borate.

Any such substance is included in the initial mix or is added to themix, such as the illustrative mixes set forth in the examples in anamount on the order of 5% or so by volume, subsequent treatment of themix being in any desired way of which the examples set forth above maybe'considered as illustrative.

The resultant final cured and hardened resin, or the final resinousproduct such as an abrasive article, even though given any desiredporosity, is now-found, when subjected to operation in the presence ofmoisture or water such as water coolant, to be well retentive of itsstrength in some cases and in others to have an effectively lower rateof loss of strength than is the case without treatment according to myinvention; thus, in any case, length of life when the product issubjected to moisture or water is increased.

To illustrate these results, some numerical comparative values takenfrom test data might be set forth such as, for example, strength testsmade of test bars which, in the tabulation of figures given below wereall of the same dimension, namely, 6 by 1" by A and which had the samerelative composition or proportions of ingredients, namely, by volume,48% of #46 Alundum" crystalline alumina abrasive grain, 22% of anilineformaldehyde resin, 10% of cryolite, 2% of soluble anhydrite, 10% of anillustrative hardening agent and .an abrasive grain wettant, namely,triglycol dichloride, and 8% of the substance added thereto according tomy invention; that is, the composition of the test bars numbered 1 to 3inclusive of Table A, while test bars numbered 4 to 6 inclusive of TableB were of similar composition excepting that. for purposes ofcomparison, the composition omitted the above-mentioned substance. Thesetest bars were soaked in water for periods of time as appear in thetables and at temperatures as indicated and these tables give comparetive strengths for each bar prior to soaking and at the conclusion ofthe soaking. thus to show the rate at which, according to my invention,as illustrated in Table A, loss of strength is opposed, in contrast tothe rate at which loss of strength occurs without treatment according tomy invention as in Table B.

Table A Midugus of I up ure Substance %?32 Temp.

initial Final Hours C. l Sodium Silicate. 36 20 1,040 4, 430 2 do 201,920 1,920 3 Zinc Bonito.-." 20 100 5, 860 850 Table 8 Naidu l'us oi upare $2! Substance fifigg Tgmp,

Initial Finn] Hours C. 4 Standard l." 36 i 20 8, 480 623 I) Ido 20 I007, 820 700 ii ..(lol '6 100 10,200 1.23};

The various substances are added to the mix in preferably dry,comminuted or powdered form, and thus they'do notcomplicate.whatevermethod of forming, shaping, molding, heat-treating,curing-or the like, it may be desired to employ in completing the resinor resinous product. Home added substance.

11 of the substances give better results than-others some are indicatedto have better effects at different temperatures than others and all ofthem are effective for practical purposes it being noted that particularrequirements as to the conditions under which the cured resin or thegrinding wheel is to operate vary as to exposure to moisture or waterand itbeing furthermore noted that the above tabulated test'data istaken from soakin tests, conditions abnormally severeas compared to eventhe severest conditions under which a grinding wheel is to operate wet.Were the data contained in these tables to be translated into graphs,the graph for each test bar would be a straight line having a certainslope, and by comparing the slopes of the graphs resulting from Table Awith the slopes of the graphs resulting from Table B, the improvedresults I am enabled to achieve according to my invention becomegraphically clearer and emphasized.

The selected substance has, in the preferred mode of carrying out myinvention, the characteristic of reacting slower tha'mor at a laterstage in point of time, than the hardening agent reacts with the resin;as a result, the cross-linking or reaction between the hardening agentand the resin is well under way or may be substantially completed by thetime the additive substance commences its reaction and ence thecross-linking can become efiective first to bring about, as by linkageor connection to the nitrogen atom or amino group, the above-mentioneduniform distribution of the halide throughout the resinous mass, andthereupon the added ingredient or substance begins to react or doesreact with the linked halide, illustratively hydrogen chloride in theabove illustrative linkages. and converts the halide into a differentphase as above noted.

This conversion, according to desire, may be complete or it may bepartial to any extent desired, according to the relative re-activity ofthe Thus, for example, the substances employed may react at a diflerentrate according to the particular hardening agent employed; their rate oftiming of re-activity may vary with temperature and hence I may eflectsome control of the rate or time of reaction of the added substancerelative to the rate of reaction of the hardening agent with the resinby suitable variation or control, during the period of time of heattreatment or curing, of the temperature under which the latter takesplace. Thus, for example, may vary, as may be desired or found suitable,the rate and extent of temperature rise during the earlier or initialcuring stages to suit. to any desired extent, the characteristics of theadded substance as to its re-activity with change in temperature so asto achieve the desired relative rates of reaction or the desired timedelay between the two.

It will thus be seen that there has been provided in this invention aresin and resinous products and a method of making the same in which thevarious objects heretofore noted together with many thoroughly practicaladvantages are successfully achieved. The halide will be seen to berendered incapable or substantially so of attracting or reacting withwater or moisture and it will be seen that I am enabled greatly toextend the field of application of these various otherwise highlyadvantageous resins and resinous products. Where employed in the makingof abrasive articles, the halide, though converted to a diflerent phaseis still available at the grinding line to contribute its beneficialaction in a grinding operal2 tion, yet a grinding wheel so made can berun wet and still have long life.

The converted phase or different stage or composition of the halide can,be physically demonstrated as can be also its physical isolation orcelllike enclosure or isolation in the hardened resin: thus, its extentor lack of reaction with water, for

practical purposes, can be shown by comparative presence of silicic acidand sodium chloride can.

be demonstrated.

Moreover, the invention is of a thoroughly practical character, has manypractical advantages, and lends itself well to adaptation to commercialproduction.

As various possible embodiments might be made of the mechanical featuresof the above invention and as the art herein described might be variedin various parts, all without departing from the scope of the invention,it is to be understood I that all matter hereinbefore set forth is to beand heating the mix at such temperatures and for such time as to'curethe resin and to cross link the aniline formaldehyde chains at the aminogroups thereof with poly-glycol dichloride, and to react the HCl' which,during the heating is bonded to the N atoms of the amino groups the Clbeing derived from the poly-glycol dichloride, with said salt of weakacid to form metal chloride and weak acid in well distributed minutequantities in said resin but chemically not a part thereof.

2. In a method-of making an aniline formaldehyde resin the steps whichcomprise mixing the active aniline formaldehyde resin with poly-glycoldichloride selected -from the group consisting of the di-, trl-, tetra-,and penta-poly-giycol dichlorides, and with sodium silicate, placing themix resulting from said mixing in a mold, pressing said mix in the mold,and heating the mix at such temperatures and for such time asto cure theresin and to cross link the aniline formaldehyde chains at the aminogroups thereof with poly-glycol dichloride, and to react the HCl which,during the heating is bonded to the N I atoms of the amino groups the Clbeing derived from the poly-glycol dichloride, with the sodium silicateto form sodium chloride and silicic acid in well distributed minutequantities in said resin but chemically not a part thereof.

3; A composition of matter capable of curing to a water resistant resincomprising aniline formaldehyde resin, a poly-glycol dichloride selectedmo em 33 from the group consisting of 111-, tri-, tetraand pentw,poly-=glycol dichlorldes and a, saltof a week acid selected from thegroup consisting of sodium silicate and zinc borate, the salt'beingCapable of reacting with the H01 which, during subsequent heating ofcomposition, becomes bonded to the N atoms of the amino groups, the Clbeing derived from the poly-glycol dichloride,

to form metal chloride and Weak acid in well-distributed minutequantities in said resin but chemically not a part thereof.

12. The product obtained by heat curing the comtioxa of claim 3.

5. A composition of matter according to claim 3 wherein the salt of theweak acid is sodium No references cited.

